Light is composed of electromagnetic waves having various wavelengths within a wavelength range of about 400 nm to about 700 nm. Each electromagnetic wave having a wavelength within this range produces light exhibiting a distinct color of light, from deep blue/purple at a wavelength of about 400 nm to deep red at a wavelength of about 700 nm. By “mixing” electromagnetic waves having different wavelengths light exhibiting various colors can be produced.
Light-emitting devices comprising a number of light sources, each light source being capable of emitting light that in general has a different color compared to the other light sources, may be utilized to provide light having a variety of colors. For example, a light-emitting diode (LED) device comprising three LEDs emitting light in different wavelength ranges (i.e. exhibiting different colors) can be utilized to provide light having virtually any color point within the triangle in a color space, for example in a chromaticity diagram, defined by three color points of the respective LEDs. By adjusting the light flux levels of the LEDs (i.e. currents through the respective LEDs) relatively to each other appropriately, there can be achieved light emitted from the LED device having different color points and/or light spectra.
For controlling the color of emitted light, conventional light-emitting devices are in general provided with a controller having a user interface that may enable a user to adjust the color of light emitted by the light-emitting device. Such user interfaces may be relatively complicated and/or non-intuitive for the user such that operation of the light-emitting device becomes relatively awkward and/or difficult. Furthermore, once the user has selected a color point of the emitted light by means of user input via the user interface, the user in general has to make a judgment as of whether the lighting atmosphere that is created by means of the selected setting is appropriate in view of the type and/or nature of the objects and/or persons that are illuminated by the light-emitting device. Thus, once the user has adjusted the settings of the light-emitting device such as to select the color point of the light emitted by the light-emitting device, the user has to determine whether the selected settings are appropriate in view of the lighting application on a ‘what-you-see-is-what-you-get’ basis.